In a kinetic study, TNF-alpha levels within the bronchoalveolar lavage (BAL) fluid increased quickly peaking at 2 h while BAL levels of IL-4, IL-5, and IL-13 peaked at later time-points. Mch hyper-responsiveness was measured 24 h after the last challenge, and mice were killed 24 h later. TNF inhibition resulted in an augmentation of these Th2 cytokines. However, the allergic pulmonary inflammation was significantly reduced by anti-TNF-alpha antibody treatment as demonstrated by a substantial reduction in the number of BAL eosinophils, lymphocytes, macrophages, and neutrophils compared with rat IgG-treated mice. Mch hyper-responsiveness was also significantly reduced in anti-TNF-alpha antibody-treated mice and the pulmonary histology was also significantly improved. Inhibition of TNF significantly reduced eotaxin levels within the lung, suggesting a potential mechanism for the beneficial effects. These data indicate that anti-TNF-alpha antibody can reduce the inflammation and pathophysiology of asthma in a murine model of asthma induced by a house dust extract.

Chromatin-modifying HDACi exhibit anti-inflammatory properties that reflect their ability to suppress DC function and enhance regulatory T cells. The influence of HDACi on MDSCs, an emerging regulatory leukocyte population that potently inhibits T cell proliferation, has not been examined. Exposure of GM-CSF-stimulated murine BM cells to HDACi led to a robust expansion of monocytic MDSC (CD11b(+)Ly6C(+)F4/80(int)CD115(+)), which suppressed allogeneic T cell proliferation in a NOS- and HO-1-dependent manner with similar potency to control MDSCs. The increased yield of MDSCs correlated with blocked differentiation of BM cells and an overall increase in HSPCs (Lin(-)Sca-1(+)c-Kit(+)). In vivo, TSA enhanced the mobilization of splenic HSPCs following GM-CSF administration and increased the number of CD11b(+)Gr1(+) cells in BM and spleen. Increased numbers of Gr1(+) cells, which suppressed T cell proliferation, were recovered from spleens of TSA-treated mice. Overall, HDACi enhance MDSC expansion in vitro and in vivo, suggesting that acetylation regulates myeloid cell differentiation. These findings establish a clinically applicable approach to augment this rare and potent suppressive immune cell population and support a novel mechanism underlying the anti-inflammatory action of HDACi.

Pulmonary inflammation causes multiple alterations within the lung , including mucus production , recruitment of inflammatory cells , and airway hyperreactivity (AHR). Measurement of AHR by direct , invasive means (eg , mechanical ventilation)or noninvasive techniques , like whole body plethysmography (WBP) , assesses the severity of pulmonary inflammation in animal models of inflammatory lung disease. Direct measurement of AHR is acknowledged as the most accurate method for assessing airway mechanics , but analysis of all data obtained from WBP may offer insights into which inflammatory aspects of the lung are altered along with AHR. Using WBP , we compared the respiratory parameters of two groups of mice sensitized with cockroach allergen. One group was treated with dexamethasone (Dex) before final challenge (DexAsthma) , while the other group received vehicle treatment (Asthma). Respiratory parameters from plethysmography revealed that Dex-Asthma mice compensated to maintain high minute ventilation , whereas Asthma mice showed significant impairment in minute ventilation despite increased peak expiratory flow (103 ؎ 5 ml/min vs. 69 ؎ 70 ml/ min). The WBP data suggest that enhanced air exchange in the Dex-Asthma mice results from significant decreases in airway mucus production. Additional studies with quantitative morphometry of histological sections confirmed that Dex reduced airway mucus. In conclusion , a detailed examination of WBP parameters can accurately assess the respiratory health of mice and will help direct additional studies. Numerous relevant animal models of disease have advanced the understanding of biology and provided important insights into the pathogenesis of human disease. The vast majority of these studies have been carried out in mice, due to their small size and the extensive characterization of the murine inflammatory system. Several robust murine models of allergic asthma have been developed in recent years, 1 including many experimental systems which induce allergic sensitization to ovalbumin (Ova). Although this system allows close control over the nature of the sensitizing agent, Ova is a relatively poor allergen and requires adjuvant co-administration or relatively high and frequent doses to achieve satisfactory immunization.2-5 Our model, conversely, uses an allergen composed of the defatted, total body extract of German cockroaches (cockroach allergen, CRA) containing appreciable lipopolysaccharide. CRA is a highly potent allergen (robust immunization is achieved with a dose thousands of times less than that required for Ova) and does not require an adjuvant for sensitization.6,7 Campbell et al 7 established the first CRA induced model of asthma in mice and demonstrated robust pulmonary inflammation with many asthma-like features. The complex nature of this allergen and its close correspondence with its urban environmental counterpart makes this model highly applicable to the study of human disease.In most models of allergic airways inflammation, disease severity and or therape...

Pulmonary LPS exposure plays a key role in exacerbation of lung diseases such as chronic obstructive pulmonary disease and asthma. However, little is known about the effects of repeated LPS exposure in the lung microenvironment. We have developed a novel murine model of pulmonary LPS tolerance induced by intratracheal (i.t.) administration of LPS. First, we show that pulmonary LPS exposure does not induce whole-body refractoriness to systemic LPS, because i.t. administration followed by i.p. administration did not decrease plasma TNF-α. However, a local refractory state can be induced with two i.t. LPS exposures. Pulmonary LPS tolerance was induced by i.t. administration of 100 ng LPS at time 0 and 48 h. Nontolerant mice received PBS at time 0 and LPS at 48 h. Bronchoalveolar lavage levels of TNF-α were significantly attenuated in tolerant mice vs nontolerant mice (1597 pg/ml vs 7261 pg/ml). TNF-α mRNA was significantly reduced in bronchoalveolar lavage cells (5-fold) and lung tissue (10-fold). No reduction was seen in neutrophil numbers in the bronchoalveolar lavage fluid, myeloperoxidase activity, or expression of neutrophil chemoattractants CXCL1 and CXCL2, reflecting the specificity of the response. The reduction in TNF-α was accompanied by a significant increase in soluble receptors, TNF-SRI (159 pg/ml vs 206 pg/ml) and TNF-SRII (1366 pg/m vs 2695 pg/ml). In conclusion, pulmonary LPS tolerance results in a specific reduction in TNF-α expression, while the neutrophilic response is unaffected. This response may be a mechanism to limit tissue damage by reducing TNF-α levels, while still maintaining the antimicrobial capacity of the lung.